how to include 'NA's in xtabs?
Thanks for your reply, but i dont want to transform my data with 'factor' or anything else. I really need 'NA's as NA's and i dont need them as levels of factor. I just seeking possibility to compute count of 'NA's with 'xtabs' without transforming my data. Maybe 'na.action' argument in 'xtabs' may help? But i dont know how to use it. Any suggestions?
Sundar Dorai-Raj wrote:
Kosenkov Kirill wrote:
Hello! I have a dataset with NA's in some variables (factors), for example: $ P67 : Factor w/ 2 levels "-","+": NA 2 1 NA NA 2 1 1 2 NA ...
The key is here. Should be 3 levels if you want NAs included.
I need to use 'xtabs' like xtabs(~x$P67) It works well and produces something like this: x$P67 - + 779 1318 but i want to compute NA's too, like this: x$P67 - + NA 779 1318 137 I am trying xtabs(~x$P67, exclude=NULL) but xtabs does not compute 'NA's in this case too. I do not want to transform my data (do not want to do any substitution on NA's). How i can say 'xtabs' to compute NA-values? and second question: how to use argument 'na.action' in 'xtabs'? 'xtabs' help page does not explain this. Thanks!
Try this:
x$P67 = factor(x$P67, exclude = NULL)
xtabs(~x$P67)
Here's an example:
R> x = factor(c(1:2, NA), exclude = NULL, labels = c("+", "-", "0"))
R> xtabs(~ x)
x
+ - 0
1 1 1
Sundar
.